In a conventional internal combustion engine, a Lenoir cycle start-type internal combustion engine is known in which the crankshaft is stopped within a predetermined crank angle range, which is midway through the expansion stroke, and start-up is carried out by supplying fuel corresponding to the amount of air in the cylinder during the expansion stroke when starting-up, and igniting and combusting the uncombusted mixture remaining in the valve (refer to Japanese Utility Model No. S60-128975, Japanese Patent Laid-Open No. JP-A-2002-317740, Japanese Patent Laid-Open No. JP-A-H11-107823, Japanese Patent Laid-Open No. JP-A-H2-271073, and Japanese Patent Laid-Open No. JP-A-2003-3887).
However, in the case in which uncombusted mixture remains in the cylinder that is in the expansion stroke when the engine is stopped, it is possible that this uncombusted mixture will self-ignite, that is, that this uncombusted mixture may combust even when the ignition signal is not ON. In addition, in the case in which the uncombusted mixture in the cylinder that is in the expansion stroke ignites and combusts when starting-up, the expansion of the combustion may be delayed and ensuring a favorable start-up becomes difficult.
In addition, in a system (what is termed an idle stop system) in which the operation of the internal combustion engine is automatically stopped while the vehicle is stopped, the stopping and starting-up of the operation of the internal combustion engine may frequently be repeated, and thus it is desirable that the start-up characteristics is further improved.
In consideration of the problems described above, it is an object of the present invention to provide a technology in which the start-up characteristics of the internal combustion engine are further improved.